mirror of
https://github.com/aicodix/dsp.git
synced 2026-04-27 22:35:45 +00:00
77 lines
1.3 KiB
C++
77 lines
1.3 KiB
C++
/*
|
|
Cyclic redundancy check
|
|
|
|
Copyright 2018 Ahmet Inan <inan@aicodix.de>
|
|
*/
|
|
|
|
#ifndef CRC_HH
|
|
#define CRC_HH
|
|
|
|
namespace DSP {
|
|
|
|
template <typename TYPE>
|
|
class CRC
|
|
{
|
|
static const int BYTES = sizeof(TYPE);
|
|
TYPE lut[BYTES * 256];
|
|
TYPE poly;
|
|
TYPE crc;
|
|
public:
|
|
CRC(TYPE poly, TYPE crc = 0) : poly(poly), crc(crc)
|
|
{
|
|
// exploit linearity of CRC only bytewise
|
|
for (int k = 0; k < BYTES; ++k) {
|
|
for (int j = 0; j < 256; ++j) {
|
|
TYPE tmp = j << (k << 3);
|
|
for (int i = 8; i; --i)
|
|
tmp = (tmp >> 1) ^ ((tmp & 1) * poly);
|
|
lut[(k << 8) + j] = tmp;
|
|
}
|
|
}
|
|
}
|
|
void reset(TYPE v)
|
|
{
|
|
crc = v;
|
|
}
|
|
TYPE operator()(bool data)
|
|
{
|
|
TYPE tmp = crc ^ data;
|
|
tmp = (tmp >> 1) ^ ((tmp & 1) * poly);
|
|
return crc = tmp;
|
|
}
|
|
TYPE operator()(uint8_t data)
|
|
{
|
|
TYPE tmp = crc ^ data;
|
|
crc = lut[tmp & 255];
|
|
for (int k = 1; k < BYTES; ++k)
|
|
crc ^= lut[(k << 8) + ((tmp >>= 8) & 255)];
|
|
return crc;
|
|
}
|
|
template <typename DATA>
|
|
TYPE operator()(DATA data)
|
|
{
|
|
for (int i = sizeof(data); i; --i) {
|
|
(*this)((uint8_t)data);
|
|
data >>= 8;
|
|
}
|
|
return crc;
|
|
}
|
|
};
|
|
|
|
template<>
|
|
uint16_t CRC<uint16_t>::operator()(uint8_t data)
|
|
{
|
|
uint16_t tmp = crc ^ data;
|
|
return crc = lut[256 + (tmp >> 8)] ^ lut[tmp & 255];
|
|
}
|
|
|
|
template<>
|
|
uint8_t CRC<uint8_t>::operator()(uint8_t data)
|
|
{
|
|
return crc = lut[crc ^ data];
|
|
}
|
|
|
|
}
|
|
|
|
#endif
|
|
|